Spot welder with electrode clamp

Abstract

A portable spot welder includes a hand-held electrode clamp assembly. The hand-held clamp has a fixed electrode and a movable electrode adapted to be moved toward and away from the fixed electrode. A spring loaded toggle is used to pivot the movable electrode to clamp a workpiece between the electrodes to exert a predetermined and repeatable pressure. The invention includes an air cooling system. Air is forced through the electrical cables connecting the hand-held electrode clamp to the welder transformer. At the hand-held clamp, the air escapes to the atmosphere through passageways near the electrodes, thereby enabling heat generated within the cables and at the electrodes to be transferred to the flowing air.

I claim: 
     
       1. A hand-held electric welding assembly for welding work pieces comprising: a. a hollow frame member having first and second ends;   b. a fixed jaw having a first end fastened at generally right angles to the first end of the hollow frame member and a second end bearing a first electrode;   c. a sleeve fastened to the second end of the hollow frame member;   d. an arm pivotally attached to the first end of the hollow frame member, the arm bearing a second electrode;   e. toggle means connected to the arm and to the sleeve for pivoting the arm to swing the second electrode into and out of operational engagement with the work piece and the first electrode;   f. a first multi-conductor insulated electrical cable affixed to the fixed jaw first end and passing through the hollow frame member; and   g. a second multi-conductor insulated electrical cable affixed to the arm and lying parallel to and adjacent the hollow frame member and passing loosely through the sleeve,   so that moving the arm by the toggle means causes the second electrical cable to slide relative to the first electrical cable.   
     
     
       2. The hand-held electrical welding assembly of claim 1 wherein the toggle means comprises spring means for producing a substantially constant predetermined working pressure on workpieces of varying thickness. 
     
     
       3. The hand-held electrical welding assembly of claim 1 wherein: a. the fixed jaw and arm are formed with respective counterbores for receiving the inner wires of the first and second electrical cables, respectively;   b. the fixed jaw and arm define respective air passages extending from the counterbores to the exteriors of the fixed jaw and arm to provide communication of the inner wires of the first and second electrical cables with ambient air; and   c. an air supply is connected to the distal ends of the electrical cables to force air through the electrical cables and through the air passages in the fixed jaw and arm,   so that the air cools the electrical cables and electrodes.   
     
     
       4. The hand-held electrical welding assembly of claim 3 further comprising: a. an electrical transformer adapted to mechanically and electrically secure the inner wires of the distal ends of the electrical cables;   b. a supply of compressed air; and   c. air inlet means mounted to the transformer for commonly connecting the electrical cables to the air supply for forcing air through the electrical cables and to the electrodes.   
     
     
       5. The hand-held electrical welding assembly of claim 4 wherein the air inlet means comprises: a. a sleeve surrounding and clamping the inner wires of each electrical cable, the sleeves being firmly electrically and mechanically connected to the transformer, the sleeves extending along the inner wires and being partially covered by electrical cable insulation, each sleeve having a wall that defines a passage therethrough; and   b. an air inlet tube connecting the sleeve passages to the air supply,   so that air from the air supply flows through the air inlet tube, through the sleeve passages, and thence through the interior of the electrical cables to the first and second electrodes.